Regulation of immune response

ABSTRACT

Androsta-5,7-diene-3β,17β-diol, its esters and ethers and related compounds wherein ring opening of the steroid ring system between carbons 9 and 10 has occurred are active as regulators of immune response and cell proliferation and differentiation.

FIELD OF THE INVENTION

This invention relates to compounds having activity as regulators ofimmune response and cell proliferation and differentiation. Compositionsof the invention comprise androsta-5,7-diene-3β,17β-diol its esters andethers and related compounds wherein there has occurred ring opening ofthe steroid ring system between carbons 9 and 10.

BACKGROUND OF THE INVENTION

Loria has disclosed that dehydroepiandrosterone,androst-5-ene-3β,17β-diol (AED) and androst-5-ene-3β,7β,17β-triol (AET)are effective as enhancers of immune response (U.S. Pat. Nos. 5,077,284and 5,206,008, incorporated herein by reference in their entirety). AEDand AET have been shown to buffer the effects of hydrocortisone bycounteracting the suppressive effects of hydrocortisone on lymphocyteproliferation. Furthermore, under infectious disease conditions, bothAED and AET positively enhance lymphocyte proliferation anddifferentiation of cells.

In vertebrates the development of host protection against pathogensrequires a selective host immune response that involves the mobilizationof the humoral and/or cellular mediated immune responses. Severalfactors adversely affect the body's protective response capability bycausing prolonged immuno-suppression or "down-regulation" of the immunesystem. It is, in reality, more appropriate to speak of "mal-regulation"or "deregulation" of the immune system than of "down-regulation" sincethe result is a failure to protect the body from assault orover-reaction to its immune response. Immuno-suppression provides anopportunity for pathogens to grow in the host. It does not matter whatcauses the primary insult to immunity. The resulting inability to musterthe appropriate immune response has the same effect. Among the manydifferent causes of immuno-suppression are viral, bacterial, fungal,yeast and parasitic infections, chemotherapy, irradiation, severestress, chronic fatigue syndrome, diabetes mellitus, autoimmunediseases, and some forms of steroid therapy.

It has long been known that patients receiving steroid hormones ofadrenocortical origin at pharmacologically appropriate doses showincreased incidence of infectious disease. A. S. Fauci, immunolo. rev.65, 133-155 (1982); and J. E. Parillo and A. S. Fauci, Annual Review ofPharmacology and Toxicology 19, 179-201 (1979). Dehydroepiandrosterone,also known as 3-β-hydroxyandrost-5-en-17-one or dehydroiso-androsterone(referred to hereinafter as DHEA), is a 17-ketosteroid which isquantitatively one of the major adrenocortical steroid hormones found inmammals. M. E. Windholz, The Merck Index, Ninth Edition (1976); K. Diemand C. Lentner, Geigy Scientific Tables (1975). (Although DHEA appearsto serve as an intermediary in gonadal steroid synthesis, the primaryphysiological function of DHEA has not been fully understood. It hasbeen known, however, that levels of this hormone begin to decline in thesecond decade of life, reaching 5% of the original level in theelderly.)

The above-referenced U.S. Pat. No. 5,077,284 entitled "Use ofDehydroepiandrosterone to Improve Immune Response" describes thesubcutaneous or oral administration of DHEA to improve the host'sresponse to infections. U.S. Pat. No. 4,978,532 describes use of patchtechnology to deliver DHEA.

DHEA is a precursor in a metabolic pathway which ultimately leads tomore powerful agents that increase immune response in mammals. That is,DHEA acts as a biphasic compound: it acts as an immuno-modulator whenconverted to androstenediol (androst-5-ene-3β,17β-diol, βAED) orandrostenetriol (androst-5-ene-3β,7β,17β-triol, βAET). However, in vitroDHEA has certain lymphotoxic and suppressive effects on cellproliferation prior to its conversion to βAED and/or βAET. It is,therefore, postulated that the superior immunity enhancing propertiesobtained by administration of DHEA result from its conversion to moreactive metabolites.

Regulation of the immune system using the active agents of the inventionwould make it possible to more safely use chemotherapeutic agents. Ithas previously been disclosed in the aforementioned U.S. Pat. No.5,206,008 that βAED and βAET (asteroid found in the skin, otherepithelial tissue and neuronal tissue) enhance immune response andlymphocytic cell proliferation.

Androsta-5,7-diene-3β,17β-diol has been prepared fromandrost-5-ene-3β,7β,17β-triol by Butenandt et al., Berichte, 71,1316-1322 (1938) at page 1321, which is incorporated herein by referencein its entirety. Androsta-5,7-diene-3β,17β-diol was also prepared fromandrost-5-ene-3β,17β-diol by Milas et al., J. Am. Chem. Soc., 68, 738-40(1946). Both Butenandt and Milas prepared the compound for the purposeof investigating whether it would exhibit antirachitic activity, but noactivity was found by either investigator. Butenandt also examined thesex hormone properties of androsta-5,7-diene-3β,17β-diol and determinedthat it was slightly active in the capon comb test for androgenicactivity and also slightly active when used in the immature female ratvagina test for estrogenic activity. Both activity levels were about1/10 the corresponding activities of androst-5-ene-3β,17β-diol (AED),which in turn has been considered to have very weak androgenic andestrogenic properties. Further, Butenandt and Milas neither investigatednor suggested that androsta-5,7-diene-3β,17β-diol might have anypractical medicinal applications. In fact, Butenandt concluded thatandrosta-5,7-diene-3β,17β-diol had no significant physiologicalactivity.

DETAILED DESCRIPTION OF THE INVENTION

It is the purpose of this invention to provide compositions for use asregulators of immune response and of cell proliferation. Thecompositions include androsta-5,7-diene-3β,17β-diol, its esters andethers, and 9,10-secoandrosta-5,7,10(19)-triene-3,17β-diol, its estersor ethers. Exposure of a solution of androsta-5,7-diene-3β,17β-diol orits esters or ethers (I) to ultraviolet irradiation (275-300 nm) atabout mammalian body temperature (35°-40° C.) causes ring openingbetween C₉ and C₁₀ to form9,10-secoandrosta-5,7,10(19)-triene-3,17β-diol, its esters or ethers(II), as the case may be.

More particularly, androsta-5,7-diene-3β,17β-diol and its derivatives(I) and 9,10-secoandrosta-5,7,10(19)-triene-3β,17β-diol and itsderivatives (II) are represented by the formulas below. ##STR1## whereineach R individually may be chosen from hydrogen, alkyl having from 1-8carbons, alkenyl having from 2-8 carbons, phenylalkyl wherein thesubstituted alkyl has from 1-4 carbons, phenyl, and COR₁, wherein eachR₁ individually may be chosen from alkyl having from 1 to about 8carbons, alkenyl having from 2 to about 8 carbons, phenylalkyl whereinthe alkyl has from 1 to about 4 carbons, and phenyl, wherein any phenylgroup may have up to three substituents chosen from among hydroxy,carboxy having from 1 to about 4 carbons, halo, alkoxy having from 1 toabout 4 carbons or alkenyl having from 2 to about 4 carbons and whereinany alkyl may be a straight chain, branched chain or wholly or partiallycyclized.

The present invention provides compositions useful for enhancing theprotective response of the immune system against infections. Themedicinal compositions of the invention are also useful for treatingother complications often accompanying immune suppression. Theenhancement of the protective immune response may also be referred toherein as up-regulation or regulation of immune response. Thecompositions of the invention alter cytokine production and promote celldifferentiation.

The use of androsta-5,7-diene-3β,17β-diol, its metabolites and theirprotected analogues as taught herein provide high levels of protectionto vertebrates, including humans, against morbidity arising frominfections or exposure to immune suppressive influences. In clinicalmedicine, treatment with androsta-5,7-diene-3β,17β-diol, its metabolitesand their analogues can lower morbidity in patients exposed topathogenic organisms. These agents can be effectively usedprophylactically in patients known to be particularly susceptible toinfection. Patients undergoing surgery or chemotherapy or patientssuffering from burns, hypoplastic or aplastic anemias, or diabetes aresuch susceptible patients who would benefit from prophylacticadministration of androsta-5,7-diene-3β,17β-diol, its metabolites andanalogues thereof. Also among the causes of immuno-suppression areviral, bacterial, fungal, yeast and parasitic infections, chemotherapy,irradiation, severe stress, chronic fatigue syndrome and some forms ofsteroid therapy. The compositions of the invention are particularlyuseful for treating patients suffering from infections which arise whenthe body's immune response has been compromised by viruses such as humanimmunodeficiency virus (HIV) and hepatitis.

Active agents of the invention may be formulated using carriers used forsteroids. The active agents may be efficiently formulated usinglipophilic carriers such as DMSO. For subcutaneous administration toanimals used in the examples, the active agents were dissolved 1:1DMSO/ethanol, then diluted for subcutaneous administration to theanimals. When the compositions are administered by mouth, they are addedto food to provide a composition containing as little as 0.01%androsta-5,7-diene-3β,17β-diol. For application to the skin, theandrosta-5,7-diene-3β,17β-diol may, for example, be dissolved in carriermaterial containing DMSO and alcohol, then applied to a patch. In suchinstances, the active agents in solution may be added to another carriersuch as glycerol before application of the composition to the supportmaterial of the patch. For vaginal or rectal administration, the activeagents may be administered by suppository, enema, or by application ofcreams, etc. Compositions of the invention may be administered by anymethod that will result in contact of the active agent with tissue ofectodermal origin. Such methods include subcutaneous or intradermalinjection or topical application. One means of topical application isthe use of skin patches impregnated with the active agent. This means ofdelivery is advantageous since it is non-invasive and easilyadministered by relatively unskilled care providers. Compositions of theinvention can also be used in veterinary medicine to prevent morbiditythat occurs during stress of shipping. Administration of the activeagents described herein can be effective as a means to prevent spread ofinfectious disease and introduction of infectious organisms into thefoods for human consumption. The active agents may be administeredparenterally by injection, in food or drink, by patches applied to theskin, or by inhalation. A particular health concern is the spread ofinfection through eggs. Eggs are frequently infected during developmentin the hen. Compositions containing active agents of the invention maybe added to the feed or water to prevent bacterial infection in theeggs.

When patches are used on animals or birds the skin should be exposeddirectly to the patch. When a patch is used, it may be necessary topluck or shave the bird or animal to expose the skin.

Other preferred methods of administration include buccal, sublingual,nasal or endotracheal routes. Sprays may be useful for this purpose. Fornasal administration, the active agent may be delivered as a powder thatis snorted. Inclusion complexes such as cyclodextrin inclusion complexesare appropriate compositions for administration to the oral-pharyngealand nasal mucosa.

The active agents may also be given with vaccines to enhance immuneresponse and to increase host immune response to infections encounteredin the environment before effective desired antibody level is attained.These agents may be administered either in a composition containing thevaccine or may be given in a composition separate from the vaccine.

The active agents of the invention may also be administered to theintestinal mucosa by oral or rectal routes. Suppositories, theintestinal mucosa by oral or rectal routes. Suppositories, solutions foruse as retention enemas, and creams or jellies are appropriate carriersfor use in rectal administration.

Androsta-5,7-diene-3β,17β-diol, its metabolites and analogues may beapplied to the vaginal mucosa using creams, jellies, suppositories, ordouching solutions. In order to enhance immune response at the site ofexposure to infectious organisms, the compounds may be added toprophylactic vaginal preparations or may be used as lubricants oncondoms.

Administration of compositions of the invention when given to patientssuffering from encephalitis and meningitis may be administeredintrathecally either at the spinal level or into the cisterna magna.

Active agents of the invention may be administered via ocular routeusing compositions in the form of drops, creams, or gel solutions orsuspensions adapted for ocular application.

EXPERIMENTAL

Androsta-5,7,-diene-3β,17β-diol (ADD) was prepared by Steraloids, Inc.using the method of the aforementioned Butenandt reference. The materialhad the following properties: m.p. 210°-212° C., [α]20_(D) -120°(methanol).

EXAMPLE 1

Use of androsta-5,7-diene-3β,17β-diol results in marked and significantresistance against viral and bacterial infection. The use ofandrosta-5,7-diene-3β,17β-diol was tested in 3 month old CD1 mice thatweighed about 23 g. Control or androsta-5,7-diene-3β,17β-diol in 1:1DMSO/Ethanol, 0.07 ml, was administered subcutaneously. 2 hours laterSimliky Forest Virus (SFV) plus the control or amount of compoundindicated in Table I was administered i.p. At the dosages administered,the results (Table I) did not appear to be dose related.

                  TABLE I                                                         ______________________________________                                                       death at  death at                                                            5 PFU/mouse                                                                             50 PFU/mouse                                         ______________________________________                                        DMSO:Ethanol + SFV                                                                             3/6         6/6                                              (control)                                                                     androsta-5,7-diene-3β,17β-diol                                                       0/6         4/6                                              0.5 mg + SFV                                                                  androsta-5,7-diene-3β,17β-diol                                                       2/6         3/6                                              2.5 mg + SFV                                                                  ______________________________________                                    

EXAMPLE 2

The use of androsta-5,7-diene-3β,17β-diol was tested in 28 day old CD1mice that weighed about 16-17 g. Androsta-5,7-diene-3β,17β-diol in 1:1DMSO/ethanol and control DMSO/ethanol (0.07 ml) were administered to therespective mice subcutaneously on day 1 followed by administration ofWest Nile Virus (WNV) in combination with the control or amount ofcompound indicated in Table II, i.p. on day 2. An additional dosage of0.5 mg. of androsta-5,7-diene-3β,17β-diol in 1:1 DMSO/ethanol wasadministered to the test animals on day 3. The results (Table II) didnot appear to be dose-related at the dosages administered.

                  TABLE II                                                        ______________________________________                                                                 death/sample                                                        death/sample                                                                            50 PFU/mouse                                                        5 PFU/mouse                                                                             Day 7   Day 10                                       ______________________________________                                        DMSO:Ethanol + WNV                                                                             3/6         5/6     6/6                                      (control)                                                                     androsta-5,7-diene-3β,17β-diol                                                       0/6         3/6     3/6                                      0.5 mg + WNV                                                                  androsta-5,7-diene-3β,17β-diol                                                       2/6         3/6     3/6                                      2.5 mg + WNV                                                                  ______________________________________                                         (mortality in controls occurred on days 7-9, in treated group on days         8-10)                                                                    

The carrier used in a given instance will depend on the mode ofadministration. Since the active agents are steroids or steroid-like,solvents for lipophilic steroids are known in the art and would be usedas carriers for these compounds. Examples of such carriers are glycolssuch as polypropylene glycol, polyethylene glycol and cyclodextrins,especially the intrinsically amorphous cyclodextrins. Other vehiclesthat should be considered include fatty acid esters of polyoxyethylenesorbitan (Tweens) or sorbitan (Spans) to prepare oil-in-water emulsions.

EXAMPLE 3

Capsules of a formulation of androsta-5,7-diene-3β,17β-diol for oraladministration are prepared by containing 1 mg.androsta-5,7-diene-3β,17β-diol, 150 mg. starch, and 5 mg. magnesiumstearate. The capsules are administered daily or twice a day to achievea daily dosage of 2 mg. per day.

EXAMPLE 4

Androsta-5,7-diene-3β,17β-diol is added to the chow of the animals at arate of 0.04% of the diet.

A preparation for application to the skin or mucosa may be prepared inthe following manner:

    ______________________________________                                        Ingredient           % w/w                                                    ______________________________________                                        androsta-5,7-diene-3β,17β-diol                                                            0.1%                                                    glyceryl monostearate                                                                               3.0%                                                    propylene glycol     13.0%                                                    Petrolatum           83.9%                                                    ______________________________________                                    

When active agents described herein are administered orally, the activeagents may be utilized more efficiently if the active agents areprotected from destruction and absorption in the upper gastro-intestinaltract. The active agents are most effective when the period of exposureto the mucosa of the intestinal tract is increased. Hence use ofcapsules containing the active agents in formulations that effect slowrelease in the intestine are appropriate for treatment of intestinaldisorders such as Crohn's disease and colitis. Use of retention enemasfor treatment of inflammation of the large bowel is also appropriate.

EXAMPLE 6

A formulation for administration as a retention enema may be formulatedin the following manner:

    ______________________________________                                        Ingredient           w/w %                                                    ______________________________________                                        androsta-5,7-diene-3β,17β-diol                                                            1%                                                      glycerol             99%                                                      ______________________________________                                    

When the active agent is administered to the mucosa of the oral cavity,it may be administered as a buccal tablet or spray for use in theoral-pharyngeal cavity and the nasal cavities.

EXAMPLE 7

A formulation for administration of9,10-secoandrosta-5,7,10(19)-triene-3β,17β-diol is prepared for oraldosage form in a soft gelatin capsule:

    ______________________________________                                        Ingredient           Amount mg/capsule                                        ______________________________________                                        9,10-secoandrosta-5,7,10(19)-triene-                                                               0.0001-0.010                                             3β,17β-diol                                                         butylated hydroxytoluene (BHT)                                                                     0.015                                                    Butylated hydroxyanisole (BHA)                                                                     0.015                                                    Fractionated coconut oil                                                                           160.0                                                    ______________________________________                                    

1. Mix BHT and BHA in coconut oil and warm to about 50° C.

2. Add 9,10-secoandrosta-5,7,10(19)-triene-3β,17β-diol to coconut oilmixture under nitrogen.

3. Fill soft capsules with the9,10-secoandrosta-5,7,10(19)-triene-3β,17β-diol/oil mixture.

EXAMPLE 8

Solution of 9,10-secoandrosta-5,7,10(19)-triene-3β,17β-diol forintravenous administration is formulated as a sterile, isotonic aqueoussolution. 1 ml contains:

    ______________________________________                                        9,10-secoandrosta-5,7,10(19)-triene-3β,17β-diol                                               1-2    μg                                        Polysorbate 20            4      mg                                           sodium chloride           1.5    mg                                           ______________________________________                                    

The compositions could also be administered to the bronchial tree viainhalation. This means of administration would be particularly useful intreating patients with lung infections or in treating other lungconditions such as black lung disease or emphysema that often arecomplicated by opportunistic infections. The compositions could be givenby aerosol into the trachea or administered in mist along with otheragents used in respiration therapy.

The administration of the active agents to the skin can be accomplishedusing patches wherein a support is impregnated with the active agent orusing implants that provide slow release of the active agents.

Patches for the administration of androsta-5,7-diene-3β,17β-diol andother active agents described herein can be formulated as adhesivepatches containing the drug. For example, the patch may be a discoid inwhich a pressure-sensitive silicone adhesive matrix containing theactive agent may be covered with a non-permeable backing. The discoidmay either contain the active agent in the adhesive or may have attachedthereto a support made of material such as polyurethane foam or gauzethat will hold the active agent. Before use, the material containing theactive agent would be covered to protect the patch.

The administration of the active agents to the skin can be accomplishedusing patches wherein a support is impregnated with the active agent orusing implants that provide slow release of the active agents.

Patches for the administration of androsta-5,7-diene-3β,17β-diol andother active agents described herein can be formulated as adhesivepatches containing the drug. For example, the patch may be a discoid inwhich a pressure-sensitive silicone adhesive matrix containing theactive agent may be covered with a non-permeable backing. The discoidmay either contain the active agent in the adhesive or may have attachedthereto a support made of material such as polyurethane foam or gauzethat will hold the active agent. Before use, the material containing theactive agent would be covered to protect the patch.

EXAMPLE 9

A patch composed of trilaminate of an adhesive matrix sandwiched betweena non-permeable backing and a protective covering layer is prepared inthe following manner:

To a pressure-sensitive silicone adhesive composition BIOPSA™ Q7-2920(Dow Corning Corp., Midland, Mich., U.S.A.) in cyclohexane (50% w/v) isadded sufficient βAED to provide a 0.5% βAED composition. The adhesiveis applied to a polyester film to provide in successive layers toprovide about 0.5 mg of active agent per cm². The film containing theadhesive is then made into patches of 10 cm². Patches would be coveredwith a protective layer to be removed before application of the patch.Patches may be prepared containing permeation enhancers such ascyclodextrin, butylated hydroxyanisole, or butylated hydroxytoluene.However, it should be remembered that the active agents of thisinvention are effective on application to the epidermal tissue. When thepatches are to be applied to thin or abraded skin, there is little needto add a permeation enhancer.

Compositions of the invention can be administered as a prophylacticduring radiation therapy or chemotherapy or after exposure toirradiation whether the exposure occurs as a result of environmentalaccident or therapy. Other instances when use of these immuneup-regulators would be appropriate is in treatment of burns, hypoplasticand aplastic anemias, diabetes, and in the elderly during epidemics.Their use is also beneficial in preventing or mitigating effects ofexposure to dangerous infectious organisms, as was demonstrated by thedata related to cardiopathies and pancreopathies. Such use isparticularly indicated in populations exposed to organisms that targetthe immune system, such as HIV infections. In certain instances thecompositions taught herein can also be used as immune modulators in theproduction of blocking antibodies to counteract hypersensitivityreactions.

As indicated previously, patients scheduled to undergo bowel surgery orother "dirty" surgical procedures could receive a dose of the activeagents as taught herein prophylactically. Use of the compositions astaught herein before invasive dental procedures or oral surgery shouldbe considered.

The active agents described herein may be used as adjuncts invaccination to increase response to an immunogen, to increase responseto the vaccine, and to protect against disease before the body hasresponded with increase in specific antibodies. Such use is particularlyappropriate in instances where inhibition of immune response can be acomplicating factor as is the case in patients suffering from, forexample, malignancies, AIDS, or environmental factors such as exposureto pesticides. It is, of course, understood that use as adjunct tovaccination would be appropriate in vertebrates other than man,including vaccination of pets, dairy animals, meat-producing animals,fish, and chickens. Chickens are particularly prone to developinfectious diseases when living in confined conditions. Coccidiosis,Salmonella infections, viral infections, including those giving rise tomalignancies such as leukemia and sarcoma (caused by a retrovirus) areparticularly common among chickens grown under modern commercialconditions.

In vitro, these compounds can be used in a commercial setting to inducecell differentiation. The use of the active agents would increase yieldof products of such proliferation in tissue culture. In the clinicalsetting, the compositions may be administered to effectively enhancepatients' ability to combat infections.

The active agents disclosed herein regulate cytokine production, thuseffecting cell differentiation. Compositions of the invention alsoencourage cell differentiation, which would benefit patients sufferingfrom malignancies such as melanoma and leukemia.

The compositions of the invention may also be used prophylactically toprotect animals from the consequences of infection by pathogenicorganisms. It is known that under the stress of shipment to marketanimals often become susceptible to infections that are not ordinarilyserious, but that can cause the animals to loss much weight en route tothe packing house. Such loss may be avoided by administration ofandrosta-5,7-diene-3β,17β-diol or9,10-secoandrosta-5,7,10(19)-triene-3β,17β-diol or their esters orethers as disclosed herein. The active agents can be given by patch,injection, or in feed. Because the active agents are most effective whenthe period of exposure to the tissue of ectodermal origin is extended,when the active agents are administered through the GI tract,compositions should be modified to extend the period of exposure of theactive agent to the intestinal mucosa and to protect the agents fromdestruction in the upper GI tract. Hence, use of capsules that effectslow release in the intestine is appropriate. The capsules may be placedin baits for administration to animals. To treat infections of the largebowel, the active agents may be given by retention enema.

The active agents may be administered to the mucosa of oral, pharyngeal,and nasal cavity by tablet, a lozenge, by administration as a spray foruse in the oral-pharyngeal cavity, or as a nasal spray.

Administration to the skin may be accomplished using patches wherein asupport to be applied to the skin is impregnated with the active agent.If the host is a mammal or bird, it may be necessary to shave or pluckthe region to which the patch is applied.

A preferred method of administration of the diene or triene, or theirethers or esters, is by subcutaneous injection as a depo. The method isparticularly appropriate for administration of the active agents tomammals, since subcutaneous injection is easily performed and the effectis relatively long lasting.

The dosages used will depend on the size and condition of the host. Testdata indicated in this application was obtained in small animals. Inlarger adult mammals daily dosage of 0.1 to 30 mg/da. ofandrosta-5,7-diene-3β,17β-diol is a preferred dosage. For compounds ofthe irradiated species having the steroid ring open at between the 9 and10 carbons, the preferred dosage is usually in the range of 0.001 to 20mg/da, with 0.001 to 1 mg/da. being the more preferred dosage. However,the dosage will vary depending on the route of administration.Subcutaneous, inhalation and intrathecal administration are methods thatwould require lower dosages of the active agents.

It is, of course, understood that analogues ofandrosta-5,7-diene-3β,17β-diol or9,10-secoandrosta-5,7,10(19)-triene-3β,17β-diol having protective groupscan be administered to the host as a means of delivering them to targettissues. Acylation is a preferred method of protecting the compounds.Acylated compounds wherein R₁ is COR₂ are also appropriate compounds foruse as starting material from which to make analogues.

The active agents can be given in conjunction with other active agentswhich may be given simultaneously or may be incorporated in compositionscontaining the active agents described herein and can be given withanti-infective agents such as antibiotics, antiviral agents,antifungals, antiparasitic agent to potentiate the activity of thesedrugs by up-regulating protective immune response. Antiviral agentsinclude, for example, dideoxyinosine, AZT, acyclovir, etc.

Finally, medicinal compositions of the invention are particularlyvaluable for use in combating infections in patients whose immunedefenses have been damaged by immuno-suppressive therapy. One of themajor complications in patients with tissue transplants is theopportunistic infection with viruses that ordinarily do not causeserious disease symptoms. Use of the compositions of the invention,which result in rapid protective regulation of the immune response,allows the medical team to place the patient on "see-saw" therapy toavoid transplant rejection while regulating the immune response to avoidoverwhelming infection.

We claim:
 1. A method of enhancing immune response in a mammal by theadministration of an immune enhancing-effective amount of a compositioncontaining as an active agent at least one compound of the formula:##STR2## wherein each R individually is chosen from hydrogen, alkylhaving from 1-8 carbons, alkenyl having from 2-8 carbons, phenylalkylwherein the alkyl has from 1-4 carbons, phenyl, and COR₁, wherein eachR₁ individually is chosen from alkyl having from 1 to about 8 carbons,alkenyl having from 2 to about 8 carbons, phenylalkyl wherein the alkylhas from 1 to about 4 carbons, and phenyl, wherein any phenyl group mayhave up to three substituents chosen from among hydroxy, carboxy havingfrom 1 to about 4 carbons, halo, alkoxy having from 1 to about 4 carbonsor alkenyl having from 2 to about 4 carbons and wherein any alkyl is astraight chain, branched chain or wholly or partially cyclized.